package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collections;
import java.util.concurrent.TimeUnit;

public class SimpleRedisLock implements ILock{
    private String name;
    private StringRedisTemplate stringRedisTemplate;
    private static final String KEY_PREFIX="lock:";
    private static final String ID_PREFIX= UUID.fastUUID().toString(true)+"-";
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT=new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }

    public SimpleRedisLock(String name, StringRedisTemplate stringRedisTemplate) {
        this.name = name;
        this.stringRedisTemplate = stringRedisTemplate;
    }

    @Override
    public boolean tryLock(long timeoutSec) {
        // 获取线程标识
        String threadId=ID_PREFIX+Thread.currentThread().getId();
        // 获取锁
        Boolean success = stringRedisTemplate.opsForValue().
                setIfAbsent(KEY_PREFIX + name, threadId + "", timeoutSec, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(success); // 防止拆箱空指针异常 null 的话就是返回false
    }
    @Override
    public void unLock() {
        // 调用lua脚本来实现判断锁状态和释放锁操作的原子性
        // 调用luau脚本
        stringRedisTemplate.execute(UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX+name),
                ID_PREFIX+Thread.currentThread().getId());
    }

//    @Override
//    public void unLock() {
//        // 获取线程标识
//        String threadId = ID_PREFIX + Thread.currentThread().getId();
//        // 获取锁中的标识
//        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
//        // 判断是否一致
//        if (threadId.equals(id)) {
//            // 释放锁
//            stringRedisTemplate.delete(KEY_PREFIX + name);
//        }
//    }
}
